Weighing scales exist in many forms, from small laboratory scales to large vehicle weighing scales. Of particular interest herein are weighing scales having multiple force measuring devices, which force measuring devices may be modular in nature.
A scale having multiple force measuring devices will also typically include a frame, a load receiving surface that interfaces with the force measuring devices, and a controller and/or monitor that receives signals from the force measuring devices and typically provides a readout of the weight of an object residing on the scale.
A vehicle weighing scale is a common example of a multiple force measuring device weighing scale. A typical vehicle weighing scale includes at least one scale platform (or deck) for receiving a vehicle to be weighed. Such a scale platform is often comprised of a metal framework with a steel plate deck, or the scale platform may be comprised of concrete (typically enclosed within a steel frame). The scale platform is normally supported from beneath by a number of force measuring devices, such as load cells. Vehicle weighing scales are also typically constructed with two rows of load cells aligned in the direction of vehicle travel across the scale platform. When a vehicle is placed on the scale platform, each load cell produces an output signal that reflects the portion of the vehicle weight borne by that load cell. The signals from the load cells are added to produce an indication of the total weight of the vehicle residing on the scale platform of the weighing scale.
Vehicle weighing scales, and their associated scale platforms, can be of various size. For example, such vehicle weighing scales are commonly of a size that is sufficient to accommodate a multi-axle vehicle, such as a semi-truck trailer. Vehicle scales of such size may be assembled using multiple scale platform segments (modules) that are connected end-to-end to provide a full-length scale platform.
As should be obvious, the ability to monitor a weighing scale for proper function is desirable. In order to do so, a monitoring methodology must be developed and particular scale behavior, or the behavior (e.g., operating characteristics) of one or more scale components must be evaluated.
It is known to evaluate weighing scale function by monitoring the operational characteristics of the scale's force measuring devices. More particularly, one or more selected force measuring device operational characteristics may be monitored and compared to a corresponding expected operational characteristic. Associated threshold values may then be set around the expected operational characteristic, with a reading below or above said threshold values being indicative of improper operation or some other problem.
A negative issue associated with such a known evaluation methodology is that of setting individual component operating characteristic threshold values. The threshold values are generally set to trigger an alarm or to provide some other notice or indication if monitored force measuring device operational characteristics exceed the preset threshold values. However, in practice it is often difficult to determine the correct individual component operating characteristic threshold value to apply. For example, an individual component operating characteristic threshold value that is set too low may trigger false alarms, while a threshold value that is set too high may not trigger an alarm when a problem actually exists. This problem may be exacerbated when the normal value range for a given operating characteristic is very small. Likewise, it may also be particularly difficult for an end user without appropriate technical knowledge and/or training to select appropriate individual component operating characteristic threshold values, which may be required in some cases.
From the foregoing discussion, it should be apparent that there is a need for improved weighing scale diagnostic methods. Exemplary method embodiments described herein satisfy this need.